1. Field of Disclosure
This invention relates to NFC communicators and devices comprising NEC communicators.
2. Related Art
Near field RF (radio frequency) communication requires an antenna of one near field RF communicator to be present within the alternating magnetic field (H field) generated by the antenna of another near field RF communicator by transmission of an RF signal (for example a 13.56 Mega Hertz signal) to enable the magnetic field (H field) of the RF signal to be inductively coupled between the communicators. The RF signal may be modulated to enable communication of control and/or other data. Ranges of up to several centimeters (generally a maximum of 1 meter) are common for near field RF communicators.
Near field communication may be referred to as near-field RFID (Radio Frequency Identification) or near-field communication. NFC communicators are a type of near field RF communicator that is capable of both initiating a near field RF communication (through transmission or generation of an alternating magnetic field) with another near field RF communicator and of responding to initiation of a near field RF communication by another near field RF communicator. Hence NFC communicators can act as both RFID transceivers and RFID transponders and are able to communicate with other NFC communicators, RFID transceivers and RFID transponders. The term “near field RF communicator” includes not only NFC communicators but also initiating near field RF communicators such as RFID transceivers or readers that are capable of initiating a near field RF communication but not responding to initiation of a near field RF communication by another near field RF communicator and responding near field RF communicators such as RFID transponders or tags that are capable of responding to initiation of a near field RF communication by another near field RF communicator but not of initiating a near field RF communication with another near field RF communicator.
Examples of near field RF communicators are defined in various standards for example ISO/IEC 18092 and ISO/IEC 21481 for NFC communicators, and ISO/IEC 14443 and ISO/IEC 15693 for near field RF communicators.
NFC communicators may be provided as standalone or discrete devices or may be incorporated within or coupled to or otherwise associated with larger electrical devices or host devices (referred to below as NEC communications enabled devices) to enable those devices to communicate by the near field with other near field RF communicators or devices incorporating or coupled to such near field RF communicators. When incorporated within a larger device or host, an NFC communicator may be a discrete entity or may be provided by functionality within the larger device or host. Examples of such larger devices or host devices are, for example, cellular telephone devices, portable computing devices (such as personal digital assistants, notebooks, lap-tops), other computing devices such as personal or desk top computers, computer peripherals such as printers, or other electrical devices such as portable audio and/or video players such as MP3 players, IPODs®, CD players, DVD players. Other examples of such larger devices or host devices are other electrical or electronic products, for example consumer products such as domestic appliance or personal care products, and other electrical or electronic devices, apparatus or systems. Some areas of application are payment systems, ticketing systems, for example in tickets (for example parking tickets, bus tickets, train tickets or entrance permits or tickets) or in ticket checking systems, toys, games, posters, packaging, advertising material, product inventory checking systems and so on.
NFC communicators generally need to achieve a pre-determined communications range. The magnetic environment experienced by an NFC communicator will affect the strength of the inductive coupling between NFC communicators and thus the range over which the NFC communicator can operate. This magnetic environment may vary depending upon the application for which the NFC communicator is intended, for example depending upon the location in which the NFC communicator is intended to operate and the magnetic environment provided by any host device, which will in turn be dependent upon the magnetic characteristics of that particular host device so that different host devices may have different effects on the communications range of the NFC communicator. Achieving the required communications range for a particular application may therefore require adjustment of the antenna circuit of the NFC communicator to compensate for the magnetic environment in which the NFC communicator is intended to be used so as to maximise the communications range. This usually requires adjustment of impedances within the inductive coupler to fine-tune the inductive coupler where the inductive coupler is a tuned antenna circuit or to null-out impedance effects in the inductive coupler where the inductive coupler is a non-tuned antenna circuit.
Where an impedance is an integrated component, that is a component forming part of an integrated circuit providing at least part of the functionality of the NFC communicator, then that component is usually a fixed-value component whose value can generally only be adjusted during manufacture of the integrated circuit, normally requiring alteration of the metal mask of the integrated circuit. This may mean that a different metal mask will be required for NFC communicators to be used in different applications so as to adjust the antenna circuit for the magnetic environment that the NFC communicators will experience in those applications. Another way to adjust the antenna circuit impedance is to add impedance components externally of the integrated circuit. Although providing such external impedance components avoids the need for mask alteration, providing external components increases the complexity of the manufacturing process and still requires selection of the actual values of the external component to fit the NFC communicator for the magnetic environment in which it is designed to operate.
The carrying out of either of the above impedance component value adjustments separately for different batches of the same NFC communicator where those batches are intended for different applications and/or for use in different host devices, increases costs and to some extent obviates the advantages of using the same NFC communicator for those different applications and/or different host devices.